1. Technical Field
The present invention relates generally to wireless communication systems; and more particularly to a wireless communication system supporting cooperative selection of frequency bands, radio frequency (RF) channels, protocols and protocol revisions for subsequent communications between the network and subscribing units operating within a service area supported by the network. Further, the present invention relates to a wireless communication system in which the necessary system operating information is contained within the broadcast messages, such operating information Used in the selection of the mode of operation (Digital or Analog) and the selection of the frequency band in which the wireless communication services are provided.
2. Related Art
Wireless communication systems are well known in the art. Such systems facilitate communication between a user of a wireless subscribing unit and users of other wireless subscribing units as well as between wireless subscribing units and users of wired units, such as those attached to the public switched telephone network. Depending upon the particular implementation, wireless communication systems may operate according to multiple protocols in particular frequency bands and on particular channels contained within the frequency bands. Frequency bands currently in use in North America and around the world for wireless communications include the 800 MHz (cellular) band and the 1900 MHz (PCS) band among others.
Various communication protocols have been developed to standardize different wireless communication technologies. These communication protocols include, for example, the Advanced Mobile Phone Service (AMPS) standards, the Narrowband Advanced Mobile Phone Service (NAMPS) standards, the Global Standard for Mobility (GSM), the Code Division Multiple Access (CDMA) standards and the Time Division Multiple Access (TDMA) standards among others. Further, these standardized protocols typically include various protocol revisions that must be accommodated, the protocol revisions further defining how additional wireless communication services and features are supported.
In most installations, a plurality of base stations managed by a mobile switching center (MSC) support wireless communications within a particular geographic area. Together, these components are referred to as a xe2x80x9cnetworkxe2x80x9d and provide wireless coverage within a service area. Typically, separate service providers maintain their own service areas which may overlap one another, each service provider maintaining a network to support its wireless service. Large geographic areas, often referred to as metropolitan trading areas (MTA), are typically serviced by multiple service providers. To maximize revenues, each service provider desires to serve a maximum number of subscribing units within the MTA. Presently, such may only be accomplished by having each user subscribe to a particular service provider.
With the advent of multiple communication protocols and technologies, in an effort to serve more subscribing units, service providers may provide wireless service in multiple frequency bands and according to multiple communication protocols. For example, the service provider may support both AMPS standards and CDMA standards on the cellular band while supporting only CDMA standards on the PCS band. While such multiple offerings may increase the potential number of subscribing units that may be served, the coordination between various communication protocols and various frequency bands within the system is required. However, the mechanism by which the system can coordinate this complex operation is not specified in the current standards. Further, because of the relative expense of supporting the multiple frequency bands and the multiple communication protocols, most service providers are limited to providing services for less than the full possible offering sets.
Manufacturers of subscribing units have responded to multiple service offerings by producing subscribing units that operate across multiple frequency bands and according to multiple protocols. For example, a multiple mode subscribing unit may support both operation under the analog AMPS (e.g., EIA/TIA-553, IS-91A) standard and operation under the digital CDMA (e.g., IS-95, IS-95B) standard which operates in multiple frequency bands. Further, in other situations, the subscribing units may operate under both AMPS (e.o., EIA/TIA-553) standard and the TDMA (e.g., IS-136) standard which operates in multiple frequency bands. However, coordinating operation for the subscribing unit in the multiple frequency bands and according to multiple protocols has proven difficult. Since the multiple mode subscribing units operating according to analog standards in multiple mode systems typically do not indicate the capability of the network, identifying operating capabilities, much less choosing from the available operating capabilities, has been difficult if not impossible.
As the number of subscribers operating within a particular service area increases, traffic within the service area also increases. Oftentimes, access and traffic channels are not available when requested and subscribers cannot access the system when desired. To compound problems, most subscribing units operate according to older analog protocols. Thus, even when sufficient bandwidth is available on the PCS bands to support communication for all multiple mode digital (CDMA) subscribing units in a certain service area, traffic problems may still exist. Further, due to shortcomings in the operation of subscribing units that can operate in both the AMPS standard and the CDMA standard, the subscribing units often fail to move to the less trafficked CDMA frequency bands due to lack of system information on the broadcast signal and lack of communication facilities between the subscribing units and the base station.
Thus, there exists a need in the art for a wireless communication system that efficiently causes subscribing units to operate among the various available frequency bands and protocols and to allow the subscribing units to request additional information from the AMPs networks regarding these frequency bands.
A wireless communication system according to the present invention facilitates wireless communication with a multiple mode subscribing unit operating within a respective service area. The wireless communication system includes a base station that provides the wireless communication within the service area in a plurality of frequency bands and according to a plurality of communication protocols. In a broadcast message on the AMPS control channel, the base station indicates to the subscribing unit the plurality of frequency bands and the plurality of communication protocols available. The subscribing unit receives the broadcast message. Based on the information provided and based on the user preferred mode of operation, the subscribing unit may decide to communicate with the base station to request additional information on one of the plurality of frequency bands. To accomplish these operations, the base station may include a broadcast message unit and the subscribing unit may include a selection unit. When all pertinent information has been exchanged, the subscribing unit, in conjunction with the network, selects a particular set of operating parameters and proceeds in operation.
The broadcast message may also include channel information that indicates the availability of a certain communication protocol and the available RF channels within the frequency bands. Further, the broadcast message may also include preference information that indicates preferred operation among the plurality of frequency bands and among the plurality of communication protocols. Additionally, the broadcast message may include preference information that indicates traffic levels within at least one frequency band of the plurality of frequency bands. Moreover, the broadcast message may include preference information that indicates available bandwidth within at least one frequency band of the plurality of frequency bands. Based upon the preference information, the subscribing unit may select operation in the frequency bands and operating protocols. The broadcast message may also include system operator information that is available to a subscribing unit. Such system operator information indicates to the subscribing unit portions of at least one frequency band reserved for the subscribing unit.
In a particular embodiment of the present invention, the plurality of frequency bands include the 800 MHz frequency band and the 1900 MHz (PCS) frequency band. In the embodiment, the plurality of communication protocols may include an analog protocol and a code division multiple access protocol such as the AMPs protocol and the CDMA protocol, respectively. However, other embodiments may support additional protocols as well.
Construction of the wireless communication system includes at least one mobile switching center and a plurality of base stations that together provide wireless coverage within the service area. The plurality of base stations are coupled to the mobile switching center and each provide wireless communication within a respective portion of the service area. In the embodiment, at least one of the plurality of base stations provides service in a plurality of frequency bands and according to a plurality of communication protocols. At least one of the plurality of base stations indicates the plurality of frequency bands and the plurality of communication protocols in a broadcast message. A subscribing unit operating within the service area receives the broadcast message, makes operational decisions and communicates with one of the base stations on a selected frequency band according to a selected communication protocol.
In the embodiment, the broadcast message may further include bandwidth information for at least one of the plurality of base stations and, based upon the contents of the broadcast message, the subscribing unit may establish communication with one of the base stations to obtain a desired bandwidth. The broadcast message may also include cost of service information for at least one of the plurality of base stations so that the subscribing unit establishes communication with one of the base stations based upon a desired cost of service.
In other embodiments, sets of base stations provide overlying wireless coverage in differing frequency bands and/or that operate according to differing communication protocols. For example, a first set of base stations may operate according to the AMPS operating protocol in the 800 MHz band, while a second set of base stations operates in the PCS band according to the CDMA operating protocol and a third set of base stations operates in the 800 MHz band according to the CDMA operating protocol. In the embodiment, the overlying systems may be supported by differing system operators, with each of the system operators providing differing types, grades and costs of service. However, two of the systems may be operated by a common operator, for example the 800 MHz AMPS system and the PCS CDMA system. However, the common operator having a installed a separate infrastructure for each of the overlying systems.
With such overlying systems installed, the operator of the system may provide broadcast messages on each commonly owned system that notifies subscribing units within the area of the existence and operating parameters of each of the overlying systems. Further, operators of competing overlying systems may agree to broadcast information regarding the overlying system of their competitor. In either case, upon receipt of the broadcast information, a subscribing unit will determine a preferred system of the overlying systems and initiate operation with the preferred system.
Moreover, other aspects of the present invention will become apparent with further reference to the drawings and specification which follow.